Dollarweed, also called pennywort, is one of the most common calls we get around Monticello, and it is one of the most misunderstood. Homeowners spray it, it browns out, and six weeks later it is back thicker than before. That is not because the herbicide failed. It is because dollarweed is a symptom, and nobody treated the cause.
Know exactly what you are looking at
Dollarweed has a round, bright green, glossy leaf with a scalloped edge, roughly the size of a coin, held up on its own little stem. It looks like a tiny lily pad standing up out of your turf. It spreads by creeping rhizomes and produces tubers underground, which matters when it comes to killing it.
The tell that separates it from its lookalike is where the stem meets the leaf. On dollarweed, the stem attaches to the center of the leaf, like an umbrella. On dichondra, which people constantly mistake for it, the stem attaches at a notch on the edge, and the leaf is more kidney-shaped and dull rather than glossy. Flip a leaf over and look. It takes two seconds and it changes what you buy.
Dollarweed means your lawn is too wet
This is the whole ballgame. Dollarweed is a wetland plant. It will grow in standing water. It shows up where turf is stressed and soil stays saturated, and it outcompetes centipede and St. Augustine in exactly those conditions. If you have dollarweed, one of these is true on your property:
- You are overwatering. Running the irrigation three or four days a week is the number one cause we find. North Florida gets real rain. Your lawn does not need daily water.
- You have a leaking or misaligned head. Walk the yard while the zone is running. A head that weeps between cycles or sprays a fence line into a puddle will grow a dollarweed patch shaped exactly like the wet spot.
- You have a low spot or a drainage problem. Heavy clay-ish soil, a compacted area, a downspout dumping into the turf, a swale that does not drain. Water sits, dollarweed moves in.
- You have shade plus poor air movement, so the ground never dries out between waterings.
Look at where the dollarweed actually is. Nine times out of ten it draws you a map. It is under the downspout, along the low side of the driveway, in the corner the head oversprays. That is your work order.
Fix the water first
If you spray without fixing the water, you are signing up to spray forever, because the conditions that favor dollarweed over your grass are still fully intact.
- Water deeply and infrequently. Aim for roughly three quarters of an inch to an inch per week total, including rainfall, in one or two soakings rather than daily sips. Set a tuna can under the sprinkler to see what you are actually applying.
- Water in the early morning so the blades dry as the sun comes up. Evening watering leaves the lawn wet all night and invites fungus on top of everything else.
- Shut the system off during our wet stretches. A rain sensor pays for itself in a summer.
- Audit every head. Fix the leaker, straighten the crooked one, cap the one hitting the fence.
- Address real drainage. Extend a downspout, aerate compaction, regrade a low spot, or cut in a drain if the water has nowhere to go.
Then help the grass compete. Thick turf crowds dollarweed out, and correct mowing height is a big part of that. See our breakdown of mowing height by grass type.
Chemical control, done carefully
Once the water is under control, herbicide finally has a chance to stick. Dollarweed is treatable, but the details matter more than usual because the products that work on it are the ones most likely to hurt your grass if you get it wrong.
Atrazine
Atrazine is the workhorse for dollarweed on centipede and St. Augustine, and it also has some pre-emergent activity, so it hits what is coming as well as what is there. Two hard limits. First, it is a cool-weather product. Labels put temperature ceilings on it for a reason, and applying atrazine when it is 90 degrees in a Jefferson County July is how people burn their lawns. Late winter into early spring, or fall, is when it works. Second, it will injure Bermuda. If you have Bermuda, atrazine is not your product.
Three-way broadleaf products
Combination broadleaf herbicides, typically built around ingredients like 2,4-D, dicamba and mecoprop, will take down dollarweed. They are also the products most likely to damage centipede and St. Augustine if the rate is wrong or the temperature is high. Some blends are labeled for those grasses only at reduced rates, and some are not labeled for them at all. This is not a place to eyeball it.
The rules that keep you out of trouble
- Read the label and follow it. It tells you which turf types the product is safe on, at what rate, at what temperature, and how often you can reapply.
- Match the product to your grass. Centipede and St. Augustine are sensitive. Bermuda and zoysia have different tolerances. A product that is fine on one can thin another.
- Do not spray in the heat of a Florida summer day. Temperature restrictions on the label are real. Spray early on a mild day, not at 2 p.m. in August.
- Plan on repeat applications. Dollarweed regenerates from tubers and rhizomes. One knockdown kills the tops, then the underground parts push new growth. Follow up at the label interval, possibly more than once.
- Do not mow immediately before or after spraying. Give the leaf surface time to take the product in.
What success actually looks like
Dollarweed is not a one-application weed. A realistic season goes like this: you find and fix the wet spot, cut back the irrigation, make a cool-season application, get a big knockdown, watch some of it return from tubers, follow up, and the patch shrinks each round while the surrounding turf thickens in and takes the ground back. By the following spring the corner that was solid dollarweed is grass again.
Where people fail is skipping step one. If the ground is still soaking, dollarweed out-competes your lawn indefinitely and no spray schedule fixes that. Worth ruling out the neighbors, too: nutsedge thrives in the same soggy conditions, often in the same patch, and it needs an entirely different herbicide. If the turf itself seems weak, a soil test through UF/IFAS Extension takes the guessing out of pH and nutrient problems.
Dollarweed is beatable, but it takes diagnosis before spraying. If you want someone to walk the yard, find the wet spot and put together a plan that fits the grass you actually have, get in touch with Williams Total Lawn Care. We work these lawns every week and we know what North Florida water does to them.